1-(4-amino-2-quinazolinyl)-piperidines and derivatives thereof containing in the piperidine-4-position "alkyl . . . alkoxy . . . hydroxy, hydroxyalkyl . . . phenyl, benzyl (and) 4-phenyl-4-carboxylic acid alkyl ester" are "hypotensive agents" according to U.S. Pat. Nos. 3,511,836 and 3,635,979. Surprisingly, the compounds according to this invention, containing the lactam-nitrogen atom in the piperidine-3 or 4-position, exhibit superior hypotensive and anti-hypertensive activity by way of the .alpha.-blocking mechanism, and a lesser tendency towards the development of tolerance.